The instant invention relates generally to improved thermally conductive drive belts for motor applications and a method of manufacturing the same. More specifically, the present invention relates to the manufacture of automotive belts, such as power transfer or drive train belts, using thermally conductive polymer compositions to overcome the traditional problems typically associated with surface heat caused by friction. While well suited for automotive applications, the belt of the present invention is also applicable for use as a drive belt in any environment where such a device is required.
In automotive applications, belts are commonly used to provide power to a variety of accessories mounted adjacent to the automobile engine. In these applications, drive belts are routed around a series of pulley wheels to transfer power from the crankshaft of the engine in order to provide power to accessories such as fans, alternators, air-conditioning compressors and other automobile components. In this arrangement, the belt makes frictional contact with the face of pulleys mounted on each of the components. The use of this type of belt and pulley system to accomplish the transfer of power to the several operation components of a motor has been proven to have certain deficiencies mainly due to the fact that the pulleys rely upon friction to provide transfer of energy from the drive belt for their motive force. In operation, the belt rotates at a high speed causing the pulleys that it comes into contact with to rotate as a result of the frictional force exerted by the surface of the belt on the surface of the pulleys. It can be seen that during their normal operational cycle these belts are exposed to a great deal of frictional force and in turn high levels of heat. This exposure to friction and heat during normal operation of these systems is often the primary reason why belts, including automotive power-train belts, quickly wear out and ultimately fail. Alternately, the build-up of heat may cause the rubber to harden thereby reducing the frictional forces between the belt and pulley causing the belt to slip, in turn further polishing the contact surface of the belt. If the frictional force is lost between the pulley and the belt, additional slippage will occur, causing either an objectionable squealing noise that will be audible to the driver as the belt slips or a change in speed of the driven accessory.
Currently, conventional multi-ribbed belts and pulleys are used on several drive systems with automobile engines. The increased surface area of the ribs enhances the overall frictional forces between the belts and the pulleys, however, as a result of the increased friction, additional heat is generated. U.S. Pat. No. 4,905,361 describes a conventional multi-ribbed pulley, designed to work with a multi-ribbed belt that includes the addition of lateral grooves that extend in an axial direction over a surface of the pulley and a roughened surface to form a higher frictional interface. Clearly, this configuration would generate even more heat due to the greatly increased frictional relationship.
Therefore, there is a desire for power-train drive belts, such as those used in automobiles, boats and other stationary engines like those used in generators, that are less prone to wear and failure due to heat and friction that they experience during use. In this regard, it is highly desirable to provide a belt that is capable of dissipating the heat generated during the normal operational cycle of the belt without the need for including separate fans and other cooling mechanisms.